Characterization and localization of the TCL-1 oncogene product.

The TCL-1 gene maps at chromosome 14q32.1 and is activated in T cell leukemias and lymphomas by either chromosome translocations or inversions that juxtapose the TCL-1 gene to the alpha/delta or the beta locus of the T cell receptor. The open reading frame of the TCL-1 gene, coding for a protein of 114 amino acids, was expressed in bacteria and antisera were raised against it. The antibodies recognized the predicted TCL-1 M(r) 14,000 protein product in cells expressing TCL-1 mRNA. Cell fractionation experiments indicated that the TCL-1 protein is present in the microsomal fraction. These results were confirmed by confocal microscopy. The TCL-1 protein has considerable sequence similarities to the product of the MTCP-1 gene on chromosome Xq28, which is involved in T cell lympho-proliferative diseases. Thus, TCL-1 may represent a member of a novel family of genes involved in lymphoid proliferation and/or survival and in T cell malignancies.